therm
Concise Oxford English Dictionary © 2008 Oxford University Press:
therm/θɜːm/
▶noun a unit of heat, especially as the former statutory unit of gas supplied in the UK equivalent to 100,000 British thermal units or 1.055 × 108 joules.
– origin 1920s: from Gk thermē ‘heat’.
'therm' also found in these Oxford entries:

